*Oriental Mysticism* (1867) by E.H. Palmer is a scholarly exposition of Sufi Islamic theology, drawn from the tradition of Islamic mysticism (tasawwuf). The text classifies spiritual seekers into ascending tiers: those whose faith rests on childhood conditioning, those whose early belief matures into reasoned conviction and surrender to God's will, and the highest class, whose faith is a direct gift of divine grace rather than inherited doctrine or personal reasoning. A central argument is that true monotheism (Unitarianism, in the Sufi sense) means perceiving God as the sole real existence — all else being either subservient to His causality or, in the more radical position, a mere illusory reflection of the divine. Palmer illustrates these ideas through two Sufi parables: an analogy contrasting night and day to argue that God cannot be positively known because nothing exists outside Him, and the Parable of the Fishes, in which fish seek to understand water by learning what it is not. The text's most distinctive quality is its sympathetic, insider-facing presentation of Sufi metaphysics — including the pantheistic or near-pantheistic claim that worldly life is a "fleeting dream" — making it valuable for readers wanting a direct engagement with classical Sufi thought rather than a detached Western critique of it.